CONVECTIVE HEAT-TRANSFER IN GASES IN THE PRESENCE OF A NONUNIFORM ELECTRIC-FIELD

The convective heat transfer coefficients h(el) and q(el) have been measured in gaseous air, O-2, N2O, N-2, F-12 and F-22 using a single platinum wire (diameter 0.025 mm) mounted along the axis of a copper cylinder (diameter 53 mm). The measurements were carried out as a function of electric field, pressure, orientation and frequency of the applied electric field in the earth's gravitation field. The convective heat transfer coefficient increases with increasing electric field. A similar trend is noted when the pressure of the gas is increased. The heat transfer coefficient also increases with increasing T-d (the temperature difference between the wire and the surrounding medium). The behaviour of q(el) at T-d congruent to 0 is found to be similar to that for T-d > 0. If is found that q(el) always increases as the inclination of the cylinder is increased from the horizontal towards the vertical. The coefficient q(el) is found to decrease linearly with frequency f.